Do CAPTCHAs Block Spam or Your Readers?

a screen shot of a CAPTCHAUnfortunately bloggers are inundated with spam comments. CAPTCHAs – Completely Automated Public Turing test to tell Computers and Humans Apart – are frequently used to weed out spambot comments from human comments.

However, because CAPTCHAs are typically images of distorted characters, this information is not accessible to screen readers, leaving people who are blind unable to post a comment. As Darrell Shandrow, a screen reader user, said visual CAPTCHAs are “no blind people allowed” signs.

CAPTCHAs do not keep out only people who are blind. With the distortion of characters or extraneous markings, people with learning disabilities, particularly dyslexia, can have difficulty deciphering what the actual characters are. Likewise, with poor colour contrast, those individuals with colour blindness or low vision can also have difficulty getting past the CAPTCHA step.

Personally, my once perfect vision is nearly forty-four years old and those darn things are stumping me more and more. Other times I don’t bother proceeding.

Screen shot of Blogger CAPTCHA with audio option One alternative is the combination of visual and audio CAPTCHA, such as the reCAPTCHA or the one on Blogger blogs. But have you ever tried listening to those ones? Totally garbled audio! If you happen to be hearing impaired and sight impaired – because disabilities don’t always come in onesies – you are completely hooped! Sorry, your opinions, ideas, expertise – or purchases! – aren’t welcomed here.

What is the solution?

Where possible, avoid using CAPTCHAs to block spam comments. Instead, use Akismet or other spam filters to control that unwanted spam. Make it as easy as possible for all readers to participate in your blog’s community.

If a CAPTCHA is absolutely necessary, use a simple text-based question – like “Which is hot: ice or steam?” – with a form field or dropdown box for the response. The key here is to keep the question simple and straightforward so as to not trip up people with cognitive impairments.

This morning I came across the WordPress plug-in is_human() with three verification methods:

  • Standard CAPTCHA Image
  • Simple Math Equation
  • Simple Custom Questions (with Question Generator)

Please do not use the image option! The other two options might be the best solution available to date, if, indeed, a CAPTCHA is necessary.

Disclaimer: I have yet to test this plug-in and am not yet vouching the plug-in is truly accessible; the concept is accessible. Your feedback is most welcomed.

What is the bottom line?

When using CAPTCHAs, be sure you are blocking spam, not your readers from commenting.

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17 Responses to Do CAPTCHAs Block Spam or Your Readers?
  1. Barbara
    October 21, 2010 | 7:07 pm

    As you know I’ve eliminated CAPTCHA, again, to give it another try. For (older than you) me, the blog has been a developmental process, a not insignificant learning curve. I may be ready to trust the platform to keep from being completely overwhelmed with spam. It is filtered and the spam file is auto-emptied on a regular basis. Basically, I don’t have to do anything except check once in a while that a real comment was mistakenly marked as spam.

    Would it be okay for you to link Askimet? I really have no reference for it.

    Thanks for this blog, Glenda, and I’m glad you were able to recover your dashboard!

  2. Glenda
    October 21, 2010 | 7:19 pm


    I think perfecting blogs is an ongoing process for all of us; constantly tweaking and trying the latest shiny objects. Bloggers can never say they have nothing to do!

    Keep me posted on how it goes with the spam filters. Akismet is available as a plug-in for WordPress. I’m not sure about other platforms.

  3. [...] This post was mentioned on Twitter by Grant Griffiths, Sheila Scarborough, Glenda Watson Hyatt , Horacio Soares, Headway Themes and others. Headway Themes said: Do CAPTCHAs Block Spam or Your Readers? via @GlendaWH [...]

  4. Adelaide Dupont
    October 21, 2010 | 9:55 pm

    I like the simple and straightforward questions like the “Is ice hot or cold”?

    • Glenda
      October 22, 2010 | 1:20 pm

      Adelaide, yes, the simple questions make the most sense. Who needs more complicated stuff in life?

  5. Graham Armfield
    October 21, 2010 | 10:27 pm

    Hi Glenda, thanks for the post.

    I’m very interested in the is_human() WordPress plugin so thanks for mentioning that. I placed it in a test blog and with Firefox and JAWS could successfully hear the question (although minus is voiced as ‘dash’). There is a link to reload it which uses javascript to update the question. I needed to shift-tab out and then tab again to hear the question, but it did get voiced.

    • Glenda
      October 22, 2010 | 1:23 pm

      Graham, thanks for testing that WordPress plug-in. It is good to know it works with JAWS with some effort.

  6. Maggie Beaumont
    October 22, 2010 | 4:27 am

    Thanks, Glenda, this info is just what I needed! I’m hoping we can ditch spam now without mistreating any of our students. I so appreciate your timely assist with this stuff.

    • Glenda
      October 22, 2010 | 1:24 pm

      Maggie, your question prompted this post. So, thank you!

  7. Indigo Jo
    October 23, 2010 | 8:14 am

    Captchas got cracked a few years ago – the British tech journalist Charles Arthur says that he got spam posted to his blog and the Captcha had been filled in. Either they are using OCR or someone in an Indian call centre is being paid to fill them in by hand.

    I run a WordPress blog and although the traffic is not that high, I hardly ever get spam landing in my main comment queue, and when it does, it’s from new spam channels or it’s stuff that I consider spam but perhaps the spammer doesn’t (e.g. bland comments from an unfamiliar commenter who advertises their product in the website space). I think Akismet and other services like it (Mollom, TypePad anti-spam) make captchas unnecessary.

    I also have blind friends, and while I experimented with the reCaptcha system, I found it didn’t work anyway on my site and abandoned it. I’ve also found that the images are sometimes ambiguous to people with perfect eyesight and the audio captchas are indecipherable. The method should be abandoned.

  8. Tina Brooks
    October 23, 2010 | 1:37 pm

    Hi Glenda,

    I don’t use captchas on my blog! I hate them myself because I often have a hard time figuring out what they are supposed to be.

    The worst ones for me are the math ones, as I have discalcula.

    I use akismet to block the spam on both of my blogs and it works like a dream.

    I never even considered that blind people can’t read them, so they can’t post. I intend to share this information every time I run into one on a blog!

    And of course, I intend to tweet this blog myself.



  9. NoSoloWeb
    October 29, 2010 | 8:51 am

    Hi, I saw this post and remembered the same question was raised at a A11Y conference I attended last week in Spain. A blind user complained that we programmers consider them hackers that want to break our sites :) Why would we use it if not to leave out the blind users?

    Well, more or less of a joke but it raised a lot of comments and the alternative of using simple “are you human” questions also was on the table. But then it came the question: how about cognitive disabilities? There are some people who do not know if the sky is yellow, how is 10+10 ..and besides, what is the difference between human and non-human? A person with Down syndrome is human or not depending on answering that question? An so on…

    So my question is if we can move on past this “are you human” questions and CAPTCHA traps. Should we think more and come up with something else? Can we find alternatives to alternatives and include people with cognitive disabilities among our website visitors?

  10. Bob Easton
    October 30, 2010 | 3:18 am

    First, CONGRATS Glenda on starting this new blog. It’s much needed and you’re a great leader for the effort.

    A couple of years before I retired from accessibility consulting (in 2008), I read a study (reference since lost) that claimed CAPTCHAs fail almost 20% of the time for people who have NO disabilities at all.

    I detest the things and often leave sites that use them. WordPress has a good alternative with Akismet, but the poor floks who use Blogger have no choice.

    If I had my way, there would be a boycott of Blogger until they come to their senses and employ real spam filtering.

  11. Graham Armfield
    October 31, 2010 | 5:10 am

    I agree that Akismet is great when used with comments on WordPress, but I don’t think it can be used with contact us forms. I’ve started getting a fair bit of spam through the contact form on my site (currently outside a WordPress setup) so really need something like Akismet that will block these spam submissions.

    Initially I was going to use ReCaptcha but then thought about the simple sums approach. Having read the above about cognitive disabilities I’m loathe to use that too.

    Is there a tool like Akismet that is available for non-Wordpress setups? And for contact forms within a WordPress setup?

  12. Graham Armfield
    November 1, 2010 | 3:18 am

    Re NoSoloWeb’s comments on cognitive disability another thought occurs to me…

    Would it be acceptable to ask for a random letter from a person’s name or email address? Eg ‘What is the 2nd letter of your first name?’

    Would people with cognitive impairments who had got as far as commenting on a blog or filling out a ‘Contact Us’ form be likely to understand that more than 2+3 or 7-2?

    This nth letter approach could be easily validated against input, but would fool most automated bots I believe since the required answer would be different for different people.

    What do you think?

  13. Glynis Jolly
    March 22, 2011 | 5:50 pm

    You’re absolutely right. I had both the Akismet and a CAPTCHA plugin going on. The Akismet is working just fine. I deleted the CAPTCHA.

  14. [...] Do you avoid CAPTCHAs? [...]

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